A fuel cell system generates electric power by an electrochemical reaction between a fuel gas and an oxidizing gas (each of which is referred to as a “reactant gas”) supplied from outside to a fuel cell. At this time, the reaction between these reactant gases generates heat. Therefore, a heat medium is supplied to the fuel cell to maintain the inside of the heated fuel cell at a constant temperature. The heat medium supplied to the inside of the fuel cell exchanges the heat in the fuel cell to be heated and discharged from the fuel cell. The discharged heat medium exchanges the heat in a heat exchanger to be cooled down, and the heat medium is again supplied to the fuel cell.
Known as the fuel cell system configured to cause the heat medium to circulate is a fuel cell power generating system capable of efficiently recovering the heat without increasing the complexity of a heat exchange medium (heat medium) passage (see Patent Document 1, for example). FIG. 8 is a schematic diagram showing a schematic configuration of the fuel cell power generating system disclosed in Patent Document 1.
As shown in FIG. 8, a fuel cell power generating system 200 disclosed in Patent Document 1 includes a fuel cell 201, a reformer 203 having a combustor (burner heater portion) 202, an anode off gas heat exchanger 204, a cathode off gas heat exchanger 205, a cooling water heat exchanger 206, and a hot water tank 207. The heat exchange medium which exchanges the heat with the heat medium (cooling water) discharged from the fuel cell 201 circulates through a circulation passage 208 connecting the anode off gas heat exchanger 204, the cathode off gas heat exchanger 205, the cooling water heat exchanger 206, and the hot water tank 207 in this order. Moreover, in the fuel cell system 200 disclosed in Patent Document 1, the anode off gas heat exchanger 204 recovers the heat by the heat exchange between an anode off gas and the heat exchange medium discharged from the fuel cell 201. Then, the anode off gas after the heat exchange is supplied as a combustion gas through an anode off gas passage 210 to the combustor 202 of the reformer 203. Moreover, water condensed in the anode off gas heat exchanger 206 is supplied to a water tank 209.
Moreover, known as a fuel cell system configured to supply the anode off gas, discharged from the fuel cell, to the combustor as the combustion gas is a fuel cell system configured to supply to the burner (combustor) the anode off gas whose moisture has been removed by a moisture remover (see Patent Document 2, for example). FIG. 9 is a schematic diagram showing a schematic configuration of a fuel cell system disclosed in Patent Document 2.
As shown in FIG. 9, in a fuel cell system 300 disclosed in Patent Document 2, the moisture of the anode off gas discharged from a fuel cell 301 is removed by a moisture remover 302, and the anode off gas is then supplied to a burner 304 of a fuel processor 303. Moreover, in the fuel cell system 300 disclosed in Patent Document 2, the moisture remover 302 is configured to store the removed moisture. Impurity ions contained in the moisture (water) having been removed by the moisture remover 302 are removed by an impurity removing means 305 (to be specific, an ion exchange of the impurity ions is carried out by an ion-exchange resin), and the water from which the impurity ions have been removed is supplied to the fuel processor 303.    Patent Document 1: Japanese Patent No. 3943405    Patent Document 2: Japanese Laid-Open Patent Application Publication No. 2006-147264